The physiology of swallowing in man is complex and poorly understood. The objective of this project is analysis of the neuromuscular mechanism by which a swallowed bolus is propelled through the pharynx into the esophagus. This work is important since disorders of swallowing cause significant morbidity and mortality. The function of the pharyngoesophageal (PE) segment is a critical part of the process of swallowing. This segment, encompassing the lower portion of the hypopharynx and the upper portion of the cervical esophagus, is closed actively when the pharynx is at rest but opens during swallowing to permit the passage of the bolus. We will study the mechanism of this activity by detailed analysis of pharyngeal wall motions and of myoelectric activity in the muscles of the pharynx. Two concurrent lines of research will be pursued. The first is precise video-radiographic measurement of pharyngeal wall motions using radiopaque suction cup markers. Preliminary studies have shown that the radiopaque marker technique demonstrates large cephalocaudal displacements which were not appreciated with traditional barium swallow videoradiography. A computer system for digitizing and processing such marker motion recordings will be used to analyze these data and the technique will then be used for detailed study of the pharynx and PE segment. The second line of research is the use of videoradiography in combination with electromyography of certain intrinsic and extrinsic muscles of the pharynx to analyze the way these muscles produce the motions of swallowing. The roles of the muscles will be studied by analyzing the temporal relationship between myoelectric activity and motion. The synergism between the inferior pharyngeal constrictors and the suspensory (or elevator) muscles of the pharynx and larynx in controlling motion of the PE segment will be a particular focus of this investigation. This research will both clarify the physiology of normal swallowing and develop techniques applicable to the study of abnormal swallowing.